1. Field of the Invention
The present invention relates to a cylinder block structure in a V-type engine. More particularly, the present invention relates to a cylinder block structure in which a means for resisting distorting horizontal forces during engine operation is introduced, wherein such means includes a bulge portion extending away from at least one side of the walls of a crank case.
2. Description of the Related Art
Conventional internal combustion vehicle engines include in-line cylinder engines, opposed-cylinder engines, and V-type engines. V-type engines have cylinder banks disposed in a relative V-shape.
Alternative configurations exist for V-type engines. In one configuration, an upper surface of a crank case mounts on a lower surface of a V-shaped cylinder block. In this configuration, an oil pan mounts on the lower surface of the crank case, and the V-shaped cylinder block supports a crank shaft in cooperation with bearing caps integrated with the crank case. In this configuration, a first and a second cylinder head are positioned on the upper surfaces of a first and a second cylinder bank.
Referring now to FIG. 8, a V-type engine 102 includes a first through an eighth cylinder (#""s 1 to #8 not shown) disposed in a V-shaped cylinder block 104 (alternatively referred to as cylinder block 104).
Cylinder banks 106A and 106B are symmetrical on one-side and an opposite-side of an engine center line EC in V-shaped cylinder block 104. Cylinder banks 106A are centered on a one-side cylinder center line CA. Cylinder banks 106B are centered on an opposite-side cylinder center line CB.
Cylinder heads 108A and 108B are symmetrical on one-side and an opposite-side of engine center line EC. A bearing construction member 110 is below cylinder heads 108A, 108B.
A crank case 112 supports V-shaped cylinder block 104. A set of bearing caps 114 (referred to as bearing caps 114) are on crank case 112. A crank shaft 116 (shown later) drives the first through eights cylinders, as will be explained. Bearing construction member 110 includes crank case 112 integrated with bearing caps 114.
An oil pan 118 is located below V-shaped cylinder block 104 and bearing construction member 110, to aid oil circulation during engine operation.
Conventionally, cylinder block 104 and crank case 112 are formed from aluminum. Bearing caps 114 are usually iron.
One-side cylinder bank 106A includes one-side cylinders 120A, specifically, the first, third, fifth, and seventh cylinders (that is, the cylinders identified with odd numbers) in one-side cylinder bank 106A. One-side cylinders 120A extend in a lengthwise direction along one-side cylinder bank 106A.
Opposite-side cylinder bank 106B includes opposite-side cylinders 120B, specifically, the second, fourth, sixth, and eighth cylinders (having even numbers) in opposite-side cylinder bank 106B. Opposite-side cylinders 120B extend in a lengthwise direction along opposite-side cylinder bank 106A.
One-side cylinder center line CA passes through the center of one-side cylinders 120A. Opposite-side cylinder center line CB passes through the center of opposite-side cylinders 120B.
One-side cylinder center line CA is set at a one-side angle xcex81 from engine center line EC. Opposite-side cylinder center line CB is set at an opposite-side angle xcex82 from engine center line EC. Engine center line EC passes through a center O of crank shaft 116. An including angle xcex1 (for example 60xc2x0) exists between engine center line EC and respective one-side and opposite-side center lines CA, CB. Including angle xcex1 is equally divided between a one-side angle xcex81 and an opposite-side angle xcex82 on respective sides of engine center line EC.
During assembly of V-type engine 102, an upper surface of crank case 112 mounts to a lower surface of V-shaped cylinder block 104. Oil pan 118 is then mounted on a lower surface of crank case 112 by an attachment fitting (not shown). V-shaped cylinder block 104, in cooperation with bearing caps 114, rotatably supports crank shaft 116 in a forward and a rearward direction along V-type engine 102.
During further assembly, respective one-side and opposite-side cylinder heads 108A, 108B are placed on the upper surfaces of each respective one-side and opposite-side cylinder banks 106A, 106B.
In bearing construction member 110, a plurality of lower mounting bolts 122, extending through bearing caps 114, mount crank case 112 on the lower surface of V-shaped cylinder block 104. Lower mounting bolts 122 integrally hold bearing caps 114 and crank case 112 to V-shaped cylinder block 104. A side mounting bolt 124 integrally holds each respective bearing cap 114 from the side of bearing construction member 110.
A main oil path 156 is in the side wall of V-shaped cylinder block 104 in a lengthwise direction. During operation, oil circulates through main oil path 156 to cool and lubricate V-type engine 102.
Referring now to FIG. 9, a first to a fifth crank journal, sequentially 126-1, -2, -3, -4, and -5 are formed on crank shaft 116 and spaced a predetermined distance from each other. A first to an eighth crank pin, sequentially 128-1, . . . -8, are also formed on crank shaft 116, in positions corresponding to respective cylinders, as will be explained.
Since V-type engine 102 is an eight-cylinder engine, first through eighth crank pins 128-1 to -8 are numbered #1 to #8 respectively for each respective cylinder.
A pair of first crank weights 130-1A, 130-1B are on either side of first crank pin 128-1. A second crank weight 130-2 is between third crank pin 128-3 and fourth crank pin 128-4. A third crank weight 130-3 is between fifth crank pin 128-5 and sixth crank pin 128-6. A pair of fourth crank weights 130-4A, 130-4B are on either side of eighth crank pin 128-8.
A first and a second crank arm 132-1, 132-2, are on either side of second crank journal 126-2. A third and a fourth crank arm 132-3, 132-4, are on either side of third crank journal 126-3. A fifth and a sixth crank arm 132-5 and 132-6 are on either side of fourth crank journal 126-4.
A pulley mounting projection 134 is on an end of crank shaft 116 adjacent first crank journal 126-1. A starter motor gear 136 on the other end of crank shaft 116 adjacent fifth crank journal 126-5.
A plurality of semicircular block side shaft holes 138 extend through the lower surface of cylinder block 104. Shaft holes 138 correspond to respective crank journal 126-1 to -5 (shown later) on crank shaft 116. In contrast to shaft holes 138, bearing caps 114 each have case side bearing portions 142. Bearing portions 142 each have respective semicircular case side shaft holes 140 corresponding to respective crank journals 126 on crank shaft 116. In operation, crank shaft 116 rotates clockwise in rotation direction R.
Referring now to FIGS. 10 to 14, crank weights 130-1 to 130-4 extend away from the moving center of crank shaft 16 (as shown), and aid in force-balancing V-type engine 102 during operation.
Referring now to FIGS. 15 and 16, bearing metals 144 rotatably support crank shaft 116 between respective block side shaft holes 138 (of cylinder block 104) and case side shaft holes 140 (of bearing caps 114).
A plurality of one-side connecting rods 146A (numbered -1 through -8) and opposite-side connecting rods 146B (numbered -1 through -8) join to crank shaft 116 and operate in respective one- and opposite-side cylinder banks 106A, 106B, as will be explained. For convenience, member specific to the fourth cylinder in V-type engine 102 are shown. (i.e. 146B-4, 120B-4, CB-4 etc.) Each one-side and each opposite-side connecting rod 146A-1 to -8 and 146B-1 to -8 has a large end and a small end.
In each one-side cylinder 120A, a set of one-side connecting bolts 150A joins the large end of each respective one-side connecting rod 146A to respective crank pins 128 with a one-side cap 148A.
In each opposite-side cylinder 120B, a set of opposite-side connecting bolts (not shown) joins the large end of each respective opposite side connecting rod 146B to respective crank pins 128 with an opposite-side cap (not shown).
A one-side piston 152A is in each respective one-side cylinder 120A. One-side piston pins 154A connect each respective one-side piston 152A to the small ends of each respective one-side connecting rod 146A.
An opposite-side piston 152B is in each respective opposite-side cylinder 120B. (i.e. opposite-side piston 152B-4 is in opposite-side cylinder 120B-4) Respective opposite side piston pins 154B connect each opposite-side piston 152B to the small ends of each respective opposite-side connecting rod 146B.
The eight-cylinders in V-type engine 102 are numbered first cylinder (#1) through eighth cylinder (#8). During operation of V-type engine 102, the respective cylinders are ignited in sequences as shown, namely, the ignition sequence is #1, #8, #4, #3, #6, #5, #7, and #2.
When V-type engine 102 operates, loads from respective one-side pistons 152A (with one-side connecting rods 146A), and the respective opposite-side pistons 152B, (with opposite-side connecting rods 146B), are applied to crank shaft 116 and received by bearing caps 114 during each cylinder ignition.
When explosion arises in the engine 102, the loads of the respective cylinders (#1 to #8 (not shown)) are applied respectively along the direction of one-side cylinder center line CA and in the direction of opposite-side cylinder center line CB.
These loads each affect V-type engine 102 differently since each is affected by the sequence of ignition and by the inertial forces of the first to fourth crank weights 130-1 to 130-4 of respective adjacent cylinders. These loads also differ for engines having 4 or 6 cylinders.
Referring now to FIG. 17, when the fourth cylinder (#4) is ignited in sequence (shown as 4S in FIG. 16), a load having a horizontal portion P4, is applied horizontally to respective bearing cap 114. When the third cylinder (#3) is ignited in sequence (shown as 3S in FIG. 16), a load having a horizontal portion P3, is applied horizontally to respective bearing cap 114.
Thus, when fourth opposite-side piston 152B-4 (of fourth cylinder (#4) in opposite-side pistons 152B) receives an explosive load along the direction of the fourth opposite-side cylinder center line CB-4, this explosive load is also applied to bearing cap 114. During receipt of this explosive load, an inertial force of third crank weight 130-3 (counter weight) of crank shaft 116 is at least twice as large as the inertial force of second crank weight 130-2 (counter weight) of crank shaft 116. Thus, as can be shown from force analysis, during ignition of fourth cylinder (#4), a resultant force FK is applied substantially horizontally to bearing cap 114. Resultant force FK is obtained by adding a resultant force F1, of a load W, and an inertial force K1, to an inertial force K2. Loads Q1, Q2 from crank shaft 116 are also applied horizontally to bearing caps 114.
A similar phenomenon arises during ignition/explosion in the sixth cylinder (#6). The resultant force (now shown) from the explosion load and the inertial force of fourth counter weight 130-4 is applied horizontally to bearing cap 114 by the affect of the above inertial force.
In the conventional cylinder block structure described above, frequent problem arise since the lower mounting bolts 122 are deformed by the horizontally applied loads from crank shaft 116, and the case side crank shaft holes (not shown) are similarly deformed. As a result of such deformation, clearances between the case side crank shaft holes and crank shaft 116 are detrimentally increased and result in damaging engine vibration and noise.
In one attempt to remedy this concern, as disclosed in the cylinder block of Japanese Patent No. 3109118, attachment brackets are positioned across a series of joint portions between a cylinder block and corresponding bearing caps and are secured to a side of the cylinder block and to the sides of the bearing caps.
Alternatively, to overcome the above disadvantage, countermeasures may include increasing the case side wall thickness of an aluminum crank case, adding a reinforcing member, or changing the material of the crank case (to use iron). Unfortunately, each of these countermeasures is accompanied by a disadvantageous weight and cost increase.
It is an object of the present invention to provide a cylinder block structure which overcomes the disadvantages described above.
It is another object of the present invention to provide a cylinder block structure with increased rigidity and a lower risk of failure.
It is another object of the present invention to increase the rigidity of a crank case to resist horizontal forces from a crank shaft and minimize load deformation while maintaining selected bearing gaps.
The present invention relates to a cylinder block structure including a plurality of mounting bolts extending through a plurality of bearing caps and a crank case to fix a crank shaft in a cylinder block. During operation, the crank shaft transmits detrimental horizontal stress to the bearing caps, the mounting bolts, and the crank case. A bulge portion, a plurality of reinforcing ribs, boss portions, and reinforcing oil transport structures extend away from the cylinder block and resist the horizontal stresses and prevent deformation of the mounting bolts and the bearing caps. An engine mount bracket secures the cylinder block structure to an external position and provides additional rigidity. The bulge portion, reinforcing ribs, boss portions and other structures minimize vibration and allow close tolerances by providing rigidity to the cylinder block structure without increasing wall thickness.
According to an embodiment of the present invention there is provided a cylinder block structure, comprising: a crank case, the crank case on a first lower surface of a V-type cylinder block, a first set of bearing caps mounted on the crank case, the cylinder block and the first set of bearing caps operably supporting a crank shaft along a center axis of the cylinder block structure, the crank shaft transmitting a distorting force to at least the first set and a one-side wall of the crank case during an engine operation, means for preventing a distortion of the at least first set and the one-side wall during the engine operation, at least a bulge portion in the means for preventing, and the bulge portion extending away from at least the one-side wall and reinforcing the first set and the one-side wall, whereby the means for preventing resists the distorting horizontal force and prevents the distortion.
According to another embodiment of the present invention there is provided a cylinder block structure, further comprising: a oil pump in the means for preventing, the oil pump mounted on a second lower surface of the bulge portion opposite the crank shaft, a first oil path in the means for preventing, a first oil path on a bulge side surface of the bulge portion opposite the crank shaft, the first oil path in fluid communication with a discharge path of the oil pump, a second oil path in the means for preventing, a second oil path on the a block side wall of the cylinder block opposite the crank shaft, and the second oil path providing fluid communication between the first oil path and a main oil path in the cylinder block, whereby the oil pump and the first and the second oil paths resists the distortion.
According to another embodiment of the present invention there is provided a cylinder block structure, further comprising: a plurality of first boss portions in the means for preventing, the first boss portions on the one-side wall and an opposite-side wall of the crank case extending away from the crank case at spaced intervals perpendicular to the crank shaft, a plurality of second boss portions in the means for preventing, the second boss portions on at least at a one-side cylinder block wall of the cylinder block extending away from the cylinder block at spaced intervals perpendicular to the crank shaft and relative to corresponding the first boss portions, an engine mounting bracket in the means for preventing, and the engine mounting bracket rigidly joining at least one of the second boss portions and at least one of the first boss portions on the one-side wall to an external support, whereby the engine mounting bracket prevents distortion of the crank case and the cylinder block relative to the external support.
According to another embodiment of the present invention there is provided a cylinder block structure, further comprising: a plurality of reinforcing ribs in the means for preventing, and the plurality of reinforcing ribs on the plurality of first boss portions on the one-side wall, whereby the reinforcing ribs stiffen the plurality of first boss portions and prevent distortion of the crank case.
According to another embodiment of the present invention there is provided a cylinder block structure, comprising: a crank case, an upper surface of the crank case on a lower surface of a V-shaped cylinder block, a bearing construction member includes the crank case and a plurality of bearing caps, an oil pan on a lower surface of the crank case, the plurality of bearing caps and the crank case rotatably supporting a crank shaft along a rotation axis in the bearing construction member, a bulge portion on at least a first case side wall of the crank case extending away from the crank case, the bulge portion having a shape and being at a position countering a distorting horizontal force from the crank shaft transmitted to the bearing caps and the crank case during an engine operation, an oil pump on a lower surface of the bulge portion, a first oil path on a bulge side surface of the bulge portion in fluid communication with a discharge path of the oil pump, and a second oil path on a block side wall of the cylinder block in fluid communication between the first oil path and a main oil path of the cylinder block, whereby the oil pump, the first oil path, and the second oil path support the bulge portion and resist the distorting horizontal load.
According to another embodiment of the present invention there is provided a cylinder block structure, further comprising: a plurality of first boss portions on the first and a second case side wall of the crank case, the plurality of first boss portions extending away from crank case at spaced intervals perpendicular to the crank shaft, a plurality of second boss portions on at least a first cylinder side wall of the cylinder block, the plurality of second boss portions extending away from the cylinder block at spaced intervals perpendicular to the crank shaft and relative to respective the first boss portions, at least one engine mounting bracket having at least an upper and a lower portion and fixed to an external support, the upper portion fixed to at least one of the second boss portions on the cylinder block on the first cylinder side wall, the lower portion fixed to at least one of the first boss portions on the crank case on the first case side wall, and the engine mounting bracket extending away from the cylinder block and the crank case to the external support, thereby preventing the distorting horizontal load from shifting the crank case, the cylinder block, and the set of bearing caps relative to the external support during the engine operation.
According to another embodiment of the present invention there is provided a cylinder block structure, further comprising: a plurality of reinforcing ribs on the plurality of first boss portions along the first case side wall, and the reinforcing ribs stiffening the plurality of first boss portions along the first case side.
According to another embodiment of the present invention there is provided a cylinder block structure, comprising: a crank case, an upper surface of the crank case on a first lower surface of a V-shaped cylinder block, a bearing construction member includes the crank case and a plurality of bearing caps, the plurality of bearing caps and the crank case rotatably supporting a crank shaft along a rotation axis of the crank case, at least a pump-mounting inclined surface on a second lower surface of the crank case, an oil pump mounted on the pump-mounting inclined surface, the pump-mounting inclined surface having a shape and a thickness countering a distorting horizontal force from the crank shaft transmitted to the bearing caps and the crank case during an engine operation, and the thickness of the pump-mounting inclined surface also increasing a rigidity of at least one case side wall of the crank case.
According to another embodiment of the present invention there is provided a cylinder block structure, comprising: a crank case; at least a first set of bearing caps mounted on said crank case; means for preventing distortion of bearing caps and said crank case during an engine operation transmitting a distorting horizontal force to said bearing caps and said crank case; a bulge portion in said means for preventing; and said bulge portion extending away from a first side wall of said crank case to reinforce at least one of said crank case and said bearing caps and resist said distorting horizontal force, whereby distortion of said cylinder block structure is prevented.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.